Survey plug



March 26, 1935. E, RAINBOTH 1,995,398

SURVEY PLUG Filed May' 7, 1934 INVENTOR EDWARnLRAlNBOTI-l ATTORNEY Patented Mar. 26, 1935 SURVEY PLUG- Edward L. Rainboth, Thet ford Mines, Quebec,

Canada Application May 7, 1934, Serial No. 724,315 6 Claims. (0112-105) This invention relates toimprovements in survey plugs used for overhead survey stations in mines, tunnels and similar places where mining or excavating operations are being carried on. The principal object is the provision of a plug that is stronger and more satisfactory in every respect as compared-with the wooden plugs now in use.

The wooden plugs commonly used for overhead survey stations in mines are subject to decay in both dry and wet mines and must be replaced at too frequent intervals to be satisfactory from the standpoint of permanency. These plugs are also frequently splintered and broken by blasting operations incident to the driving of drifts and cross cuts. This is particularly true when driving on curves and turnouts where it is necessary to have the survey line plugs close to the face. In such cases the spad is usually bent or knocked out and the plug itself frequently destroyed by flying rocks from the blasting. Another disadvantage is that the spad, being exposed and wholly unprotected, is frequently struck and displaced by drill steel or pipe carried on the shoulders of workmen passing the survey station. It also frequently happens that, in the absence of other means for hanging plumb lines, electricians and track layers frequently hang these lines from the spads of the wooden plugs and, in so doing, often bend or pull the spad free from the plug.

From the foregoing observations it will be evident that, when using wooden survey plugs, survey lines often have to be relocated owing to destruction of the plug or to bending or accidental detachment of the survey line spads. This necessitates considerable extra work on the part of the engineer or surveyor which the present invention proposes to eliminate by the provision of an all-metal plug which ensures a more permanent and stronger type of survey station and is designed so that the survey line spad is adequately protected from flying rock or accidental contact with objects carried by passing workmen.

Proceeding now to a more detailed description reference will be had to the accompanying drawing, wherein- Fig. 1 is a view, in side elevation, of my improved survey plug.

Fig. 2 is a top plan view.

Fig. 3 is a bottom plan view.

Fig. 4 is a vertical sectional view along the line 4-4 of Fi 2.

Fig. 5 is a side elevation of the plug showing it mounted in a tunnel or mine working.

Fig. 6 is a side elevation of a steel core block used inconnection with the-manufacture of the plug. In this view the shell in which the core block is fitted is indicated by dotted lines.

Fig. '7 is a top plan view of said core block.

Referring more particularly to the drawing, 5 designates'a tubular-metal shell which is cut to provide four equi-spaced slots 6, the portions of the shell lying between these slots being squeezed or compressed together so that the shell has a slight inward taper toward its upper end. The lower closed ends of the slots -6 are spaced a substantial distance above the lower end of the shell which is provided with a circular series of relap tively small openings 7. Castin the lower portion of the shell is a lead filler 8 having its upper surface 9 flush with the lower ends of the slots 6 and its lower surface 10 spaced a substantial dis tance above the lower end of the shell. the casting of the filler, portions of the lead flow into preformed grooves 11 in the shell and thus serve to securely hold the filler in place. The lower surface of the filler is provided with a plurality of preformed spad receiving sockets 12 having smooth or unthreaded walls. The spad forming element indicated at 13 is adapted to be screwed into a selected one of these sockets as shown in Fig. 4. This spad forming element is provided with a screw threaded shank 14 and a flange 14a. of the sockets in the lead filler it cuts its own thread. The spad is screwed in until the flange When this spad is screwed into one During 14a is jammed against the lower surface of the lead filler so that the spad is thus securely held in place. As shown more particularly in Fig. 4 the shell 5 projects a suflicient distance below the lead filler to form an annular guard wall around the spad which protects it from flying rock or accidental blows from implements or materials carried on the shoulders'of passing workmen.

The manner in which the plug is applied is illustrated in Fig. 5. As here shown the tapered plug is driven into a hole 16 drilled in the solid rock roof of a tunnel 17 or other mine working. The outer surface of the shell 5 is preferably chipped or otherwise provided with a number of rasp-like nicks 5a which tend to more securely anchor the shell within the opening.

When the plug is fastened in place as shown in Fig. 5 the small openings '7 at the lower end of the shell 5 may be used by drillers, trackmen, etc., for lining in, the plumb lines being hung from the hole that is nearest the line of sight by means of some form of suspension member such ing in a survey station the socket 12 in the lead filler nearest the exact line or point is located. The surveyor or his helper then screws the spad into this socket with a pair of pliers and then bends the spad to the exact position required.

In the manufacture of survey plugs designed in accordance with this invention a plurality of tubular shells such as indicated at 5 are cut from a suitable length of galvanized iron pipe and the ends of each shell faced off in a suitable manner. Each shell is then placed on a lathe by means of which the filler anchoring grooves 11 are cut around the inside of the shell. The four longitudinal slots 6 are then cut by a shaper'or milling .machine after which the portions of the shell lying between the slots are forced together by hammering or by squeezing the slotted. portion of the shell in a vise. The shell is then provided with the drill holes 7 and the rasp-like nicks 5a, the latter being chipped on the outer surface of the shell by a chipper or diamond pointed chisel. The shell is now ready for the casting of the lead filler 8. In order to cast this filler with the preformed sockets 12 a special form of core block indicated at 18 in Fig. 6 is employed. The base of this block is made of steel provided with drilled openings in which a plurality of pins or posts 19 are fastened. The core block is then inserted in the bottom of the shell 5 asshown in Fig. 6 and molten lead poured into the shell until the lead reaches the level of the lower end of the slots 6. After the lead is cooled the plug is removed from the core block and is ready forluse.

Having. thus described my invention, what I claimis:

l. A survey plug comprising a metal shell provided with slots extending from the upper toward the lower end of the shell, the inner ends of said slots being spaced from the lower end of the shell and the portions of the shell lying between the slots being crowded together to give a slight taper towards the upper end of the shell and means in the lower portion of the shell for the attachment of a survey line spad.

2. A survey plug comprising a metal shell, a

filler contained within the shell and spaced above the lower end thereof and a spad secured to said filler, said spad being surrounded and protected by the portion of the shell extending below the filler.

3. A survey plug as claim in claim 2 in which the shell is provided with a series of openings located between the filler and the lower end of the shell.

4. A survey plug comprising a metal shell, a filler contained therein, the lower portion of the shell extending below the filler to surround and protect spads secured to said filler and the upper portion of the shell being slotted.

5. A survey plug comprising a metal shell provided with inner peripheral grooves adjacent its lower end and a filler contained in said shell, said filler comprising a mass of lead having key portions extending onto said grooves and also having preformed spad receiving openings extending upwardly from its lower surface.

. 6. A survey plug comprising a metal shell provided with slots extending from the upper towards the lower end of the shell, the inner ends of-said slots being spaced from the lower end of the shell and the portions of the shell lying between the slots being crowded together to give a slight taper towards the upper end of the shell, a mass of lead secured within the shell to provide a filler having its upper surface coinciding with the lower ends of said slots and its lower surface positioned above the lower end of the shell, said filler having preformed spad receiving openings extending upwardly from its lower surface.

EDWARD L. RAINBOT H. 

